angle constrain

[Chat_Gpt]

Hi,

Is it possible to constrain the rotational angles in Euler3DTransform? If so then what is the way for imposing lower and upper bounds on rotational angles within an Euler3DTransform object during a registration process in ITK?

[dzenanz (Dženan Zukić)]

You might want to take a look at this post:

constraining parameters during optimization

For example, I’m using the Similarity2DTransform. Here, I would like to enforce that the scale must be non-zero and positive, however I would like to allow for negative translation. Is it correct, that the only optimizer which can handle constraints is the LBFGSBOptimizer? But, it looks like that I can only constraint all parameters with the same bounds - is this correct? So I tried something like this: R = sitk.ImageRegistrationMethod() R.SetInitialTransform(sitk.Similarity2DTransform()) R.…

[Chat_Gpt]

In this post they used LBFGSBOptimizer. But I am doing rigid transformation. Is there any way I can set constraints for rigid transformation?

[dzenanz (Dženan Zukić)]

Yes. The transform parameters are 3 rotation angles, and 3 translations. You can set bounds for each of them independently. From Euler3DTransform docs:

The serialization of the optimizable parameters is an array of 6 elements. The first 3 represents three euler angle of rotation respectively about the X, Y and Z axis. The last 3 parameters defines the translation in each dimension.